RAM 68.
I have one in the collection, but it's on a Crossman stock.
Going by memory, here.
Interesting internals, the bolt inside is like a mile long. Long enough they used centering screws to keep it lined up with the breech.
The body also had screws in odd places holding it together, and they had to be real short to avoid penetrating into the body cavity where the hammer goes back & forth.

Meh. It's been a while since I pulled it apart. I may even have it confused with the thunderpig...
I could dig it out & take pics.